The Parmly Hearing Institute is requesting renewal of Program Project support for a multidisciplinary program (using a comparative approach and complex, biologically relevant sounds) to study information processing by the auditory system. Research Projects: Project A-Temporal Processing by a Model Vertebrate Auditory System: The fish has been developed as a model system for studying auditory processing, especially temporal processing, and the relationship between behavior and physiology. Recent research has revealed a wide variety of neural patterns in the auditory nerve. The sources of this variability will be studied in terms of describing different neural mechanisms for coding. The long term goal is to understand central auditory processing. Project B-Lateral Line System: Past research has shown that a Lake Michigan Sculpin is a powerful model for studying the hair cell, lateral line system. The feeding behavior of the sculpin will be studied, additional description of the surface anatomy of the developing lateral line system will be undertaken, and studies of the physiology of the system are planned. The research shows greate promise in explainig the relationship between sensory processing and behavioral output in a simple sensory system and to reveal fundamental principles of information processing by a hair cell system. Project C-Localization: The study of binaural processing of complex sounds in which interaural cues are different in different regions of the spectrum will continue. Such complexity describes almost all sounds localized in normal environments. Studies of localization and recognition of signals with a few number and a large number of spectral components are planned. Project D-Complex Sound Processing: A three pronged attack (human psychophysics, animal psychophysics, and neural physiology) is proposed to study processing of complex sounds which produce 'pitch' and sounds whose spectral structure relates to sounds in reverberant environments. The human work will measure the acuity of processig these sounds. The physiological work will describe complex sound processing at the level of the Cochlear Nucleur. The animal behavioral work is crucial in forming a tie between physiology and auditory information processing by the human auditory system.